Historically, there has been a search for methods for reducing pain in warm blooded animals and especially in human beings. The search for a safe, effective, analgesic composition, which can be administered to warm blooded animals, has therefore been a continuing one since better safety and effectiveness are always desirable.
One of the most common analgesic compositions for reducing pain is aspirin or sodium acetylsalicylate. Unfortunately, aspirin has some undesirable effects especially in some individuals who are sensitive to aspirin. This sensitivity can take the form of upset stomachs and G.I. disturbances and can be allergic reactions which in uncommon cases can even cause death.
For these reasons, acetaminophen, also known as 4-hydroxyacetanilide, was developed and is marketed as an analgesic for use by those who are sensitive to aspirin. Unfortunately, while acetaminophen seems to cause fewer gastro intestinal disturbances, the toxicity of acetaminophen is undesirably high and liver damage and even death can result from ingestion of excessive quantities of acetaminophen. While some approaches have been made to reduce the toxicity of acetaminophen, none of these approaches have been very successful. Some of the problems encountered in reducing the toxicity of acetaminophen are high costs, insufficient effectiveness, reduction of analgesic effect and the use of chemicals which themselves present toxological problems.